Studies are proposed on the mechanism of oxidative and photophosphorylation, in particular, focused on evaluation of the binding-change mechanism for ATP synthesis proposed principally on basis of researches from this laboratory. One approach will be to evaluate in detail the effects of ATP concentration on oxygen exchange and hydrolysis rates catalyzed by the purified F1 ATPase, with the aim of critically assessing if the participation of alternating sites with strong subunit interaction is able to explain the observed rates. Another proposed assessment is measurement of the level of transitorily tightly-bound ADP and its catalytic competency as an intermediate. The behavior of ATPase modified by chemical derivatization will help clarify if a single rather than two different catalytic sites adequately explains the behavior and synthesis and hydrolysis. Computer programs will be used to find if the suggested mechanism accounts for experimental observations on levels intermediate states. Other experiments will probe the function of differing proteins in the ATP synthase complex. Methodologies for measurement of 180-Pi species by mass spectrometric techniques will be further developed. A longer range goal will be to measure all rate constants for both the energy-linked and uncoupled reactions.